Crumble the stock cube into a large heatproof bowl. Stir in200ml boiling water to dissolve in. Tip in the bulgar wheat and give it a quick stir. Cover with cling film or a plate. leave to soak while you prepare the rest of the salad ingredients.
Slice the skin and pith off the grapefruit. Segment the grapefruit by holding it in one hand over a bowl to catch any juice. Slice a small knife lengthways between one segment and the membrane, and then slice on the other side to free the segment from the membrane. Slide into the bowl. Repeat with the remaining segments.
Finely dice the tomatoes and add them to the bowl. Roughly chop the rocket and add that too.
Finely chop most of the parsley leaves and stem, keeping a few parsley leaves back for garnishing. Finely chop the mint leaves. Add both to the bowl. Finely grate the lemon zest into the bowl. Slice the lemon into wedges for squeezing later on.
Tip the sunflower seeds into a dry frying pan. Toast over a medium heat for 3 mins, shaking the pan, till the seeds are golden and popping. Tip into a bowl. Take the pan off the heat.
The bulgar wheat should've sucked up all the vegetable stock by now. Stir it with a fork to loosen the grains. Add the chopped fruit, veg and herbs and most of the sunflower seeds.
Add 1 tbsp olive oil and some salt and pepper to the bulgar wheat. Give it a really good stir to mix everything together. Taste and add more salt and pepper if you think it needs it. Heap the salad up on 2 warm serving plates.
Warm the frying pan for 1 min. Slice the halloumi cheese. Add ½ tbsp oil to the pan. Add the cheese slices. Fry for 4-5 mins, turning once, till golden and soft. Pile up on the salad with the last of the sunflower seeds and the remaining parsley leaves. Serve with the lemon wedges.